Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Qual ano teve uma transmissão de Voith D863.4 e um motor Cummins ISM?
 ###Tabelas: CREATE TABLE main_issuers (main_issuers_id AUTO_INCREMENT PRIMARY KEY, Currency VARCHAR, Country VARCHAR, Generic Name or Nickname VARCHAR, Rating ( S&P / Moodys ) VARCHAR, Negotiable debt at mid-2005 ( US dollar bn equivalent) INT, Government financial liabilities as % of GDP (end 2003 - source : OECD ) VARCHAR, Issuer VARCHAR, Internet site VARCHAR) CREATE TABLE college_career (college_career_id AUTO_INCREMENT PRIMARY KEY, Year VARCHAR, Games INT, Rushes INT, Rushing Yards INT, Rushing TDs INT, Receptions INT, Receiving Yards INT, Receiving TDs INT) CREATE TABLE groups_containing_sulfur (groups_containing_sulfur_id AUTO_INCREMENT PRIMARY KEY, Chemical class VARCHAR, Group VARCHAR, Formula VARCHAR, Prefix VARCHAR, Suffix VARCHAR) CREATE TABLE buses (buses_id AUTO_INCREMENT PRIMARY KEY, Fleet # VARCHAR, Year INT, Manufacture VARCHAR, Model VARCHAR, Length (ft) INT, Engine VARCHAR, Transmission VARCHAR) CREATE TABLE season_6:_1997-1998 (season_6:_1997-1998_id AUTO_INCREMENT PRIMARY KEY, No. in series INT, No. in season INT, Title VARCHAR, Director VARCHAR, Writer(s) VARCHAR, Original air date VARCHAR, Production code VARCHAR)  
SELECT Year FROM buses WHERE Transmission = Voith D863.4 AND Engine = Cummins ISM